非枝晶铝合金(A356)半固态感应加热模式及控制模型

以感应加热原理、“集肤”效应、“电磁尾端”效应和坯料表面能量损失为基础,来探讨坯料温度分布不均匀的主要 原因;利用分析软件ANSYS和实验手段模拟二次加热模式,并以电动势传感器为例介绍二次加热的控制模型。     

非枝晶铝合金(A356)感应重熔加热优化

通过分析感应加热中的“集肤”效应、“电磁尾端”效应和坯料的表面能量损失，探讨了坯料温度分布不均匀的主要原因；利用分析软件ANSYS和实验手段模拟二次加热模式，并以电动热传感器为例介绍二次加热的控制模型，获得较理想的加热曲线。     

半固态铝合金AlSi6Mg2的二次加热工艺研究

针对半固态AlSi6Mg2合金的二次加热，实验优化了线圈和坯料的尺寸，保证了坯料加热过程中各个部位的温度均匀性；制定出单工位感应加热和六工位连续加热的二次加热工艺，在六工位连续操作过程中每个坯料加热11．5min，平均每2．3min提供一个加热完成的坯料，在工艺流程上实现了二次加热和半固态压铸的很好衔接。分析了二次加热过程中的组织演变．最终得到从坯料外形到内部组织都适合于半固态压铸的坯料。     

半固态触变成形二次加热数值模拟及参数优化

半固态触变成形技术以其节省能源、成形力小和近终成形等优点受到广泛关注。通过对ZL101铝合金试样在各种不同工艺参数下的感应加热温度及温度均匀性进行的研究，运用CAE技术模拟加热频率、加热时间、线圈电流强度、线圈尺寸、加热后停留时间等参数对坯料温度场的影响，提出二次加热中获得均匀温度场的工艺条件、参数与措施。模拟结果与感应加热的实测数据具有很好的吻合性。     

立式感应加热炉温度均匀性的控制

针对感应加热炉在锫合金坯料加热过程中存在的温度均匀性问题,根据最近的调试,对相应部位线圈进行电容补偿并通过调整坯料托盘结构,增加托盘推头长度,控制了炉子加热坯料的温度均匀性.     

高碳钢感应加热的微观组织研究

应变诱发熔化激活法是一种有竞争力的半固态金属材料制备方法。通过控制感应加热条件均匀化了坯料中心和表层的温度分布,从而获得均匀的球状或近球状微观组织。采用感应加热方式把高碳钢坯料加热到半固态区域,然后液淬坯料保留其在半固态的微观组织,最后研究了感应加热后的微观组织特征。实验结果表明:在感应加热过程中,坯料的底部出现锥形冷端,锥内呈现条带状固相组织,其余部位为均匀细小的球状或近球状固相颗粒组织,圆整度良好。说明感应加热制备半固态坯料是一种理想的、很有发展前途的制备方式。     

ZL112Y压铸铝合金摩托车零件的半固态高压铸造成形

采用高频感应加热装置和温度测定装置，研究了ZL112Y压铸铝合金坯料高频感应加热二次重熔合适的半固态重熔温度、加热功率和速度，以及这些工艺参数对坯料的触变性能和微观组织的影响。结果表明：该合金合理的半固态二次重熔温度为570～571℃；在优化的感应加热工艺条件下，半固态重熔坯料内部的温差在0～1℃；半固态重熔过程使原始料坯中的α枝晶组织变成球团状和节杆状组织，满足了半固态触变成型的要求。采用实验室所获得的二次重熔工艺成功地压铸成形了JH70型摩托车发电机支架零件。     

ZL101合金半固态二次加热

采用半固态合金二次加热，对半固态坯料施加合理的二次加热路径，重新获得适于后续加工的具有近球状固相颗粒均匀分布的半固态组织。采用功率为20kW，频率为30kHz的高频感应加热装置，研究了采用再熔融加热法制备的ZL101半固态合金坯料的二次加热过程。结果表明：为了获得适于最终成形的半固态组织，有必要把半固态坯料二次加热过程分为几个加热速率不同的加热阶段，然后在半固态温度区间某一需要加工温度下进行适度保温。通过实验给出了ZL101合金半固态坯料二次加热条件，并讨论了二次加热条件对半固态组织演化的影响。     

半固态触变成形坯料二次加热技术分析

对半固态坯料二次感应加热技术进行了较为系统的介绍和分析。触变成形对坯料固相分数十分敏感 ,故控制加热温度精度十分关键。加热系统设计力求在最大软化度下的加热周期最短 ,且尽可能不出现“象足” ,为此要注意减少坯料顶部和底部的热扩散和坯料从加热系统搬运到成形机械过程中的温降。目前尚无法可靠地定量检测坯料过软化的问题 ,单靠大量试验难以改进二次加热系统。采用数值模拟和小型试验研究是实现二次加热优化设计的主要选择     

ZL112Y半固态连续触变成形料坯的温度场数值模拟

根据半固态连续触变成形的原理,自行设计了一套水平式二次重熔连续感应加热装置。采用商业软件ANSYS对该装置的3台感应加热设备不同加热功率匹配下料坯的温度场进行了计算机模拟,可得到与ZL112Y铝合金所需半固态触变温度为570-572℃相吻合的结果。而且通过模拟,获得了坯料连续式二次重熔时合理的加热参数,即大、中、小3种加热功率设备的电流分别为1350、800、600A,依次加热3min,得到的坯料温度接近于理想的半固态温度。     

The effect of globular microstructure size on the mechanical properties in reheating process of aluminum alloys

One of the important steps in semi-solid forming is the process of reheating raw materials to the semi-solid state. This process is not only necessary to achieve the required semi-solid state of the billet, but also to control the microstructure of the billet. In the reheating process, the globule size is determined by the holding time of the final reheating step. Therefore, some experiments to investigate the relationship between the mechanical properties and the holding time in the last heating step were performed. The alloys used in this experiment were 357, 319, and A390 alloys. The experiments of reheating were performed using an induction heating system with a capacity of 50 kW. This article shows the evolution of the microstructure according to the holding time of the last reheating stage. Furthermore, to evaluate the effect of globule size as determined by holding time of the final reheating step, uniaxial tension tests were performed. The stress-strain curves were plotted according to the holding time, and a relationship between the microstructure and the flow stress of semi-solid material was formulated.     

二次加热条件对泡沫镁结构的影响

研究了两步法制备泡沫镁工艺中的二次加热过程,考察了二次加热温度和时间对泡沫镁结构的影响.结果表明:通过控制加热温度和时间,采用两步法可以制备出低密度、高孔隙率、气孔分布均匀的泡沫镁;随着二次加热时间或温度的增加,泡沫镁的孔洞尺寸逐渐变大,分布逐渐变得不均匀,并出现孔洞合并的趋势;当加热时间超过20 min或加热温度超过610℃后,泡沫镁的孔洞分布变得不均匀,出现孔洞氧化与合并的现象;随着加热时间或温度的增加,泡沫镁的密度逐渐减小,平均孔隙率逐渐增加,但当加热时间超过20 min时,密度略有升高,平均孔隙率略有下降.     

Induction heating of semisolid billet and control of globular microstructure to prevent coarsening phenomena

An important step in the thixoforming process is the induction heating of the raw materials to the semisolid state. Using this technology, the process behavior is satisfactory from the point of view of reproducibility and temperature control. Therefore, the objectives of this study are to define the correct relationship between coil length and billet length for uniform induction heating and to present the optimal reheating conditions suitable for the thixoforming process (or to secure a fine globular microstructure without liquid segregation). The optimal inductive coil on the induction heating process of semisolid billet machined to 76 mm diameter and 90 mm length to reduce the temperature gradient of the billet and to obtain the globular microstructure was theoretically designed and the suitability of the designed coil dimensions verified by reheating experiments. The globular microstructures of semisolid billet in heating and holding processes were controlled to prevent the coarsening phenomena of Al-7%Si-0.3%Mg alloy and to apply to the thixoforming process. In addition, the effects of the history of processing and induction heating parameters such as reheating time, holding time, holding temperatures, capacity of the induction heating system, and adiabatic material size on the globularization were investigated. It was concluded that in the case of a three-step reheating process, the final holding time is the most important factor and 2 min is suitable to maintain a globular microstructure.     

Induction heating process of an Al–Si aluminum alloy for semi-solid die casting and its resulting microstructure

During induction heating, the relationship between time and temperature must be controlled exactly to obtain a homogeneous temperature distribution over the entire cross-sectional area. Because the initial solid fraction in the semi-solid die casting (SDC) process is the main parameter to achieve a homogeneous flow behavior of the liquid and solid phases and to prevent macro-segregation effects in the SDC process, an accurately controllable induction heating method must be selected for the reheating process. The purpose of this work is not just to obtain the desire solid fraction, generally about 50%, but also to ensure the optimal induction heating conditions of A356 alloy to reduce the temperature gradient of a 76 mmdiameter×90 mmlength billet and to obtain a fine globular microstructure without grain coarsening (resulting microstructure). This work shows that, in the case of a three-step reheating process for the SDC process, the final holding time is the most important factor to maintain a fine globular microstructure without grain coarsening.     

Reheating process of metal matrix composites for thixoforming and their inductive coil design

In this work, the fabrication processes of particulate metal matrix composites (PMMCs) with a homogeneous distribution of reinforcement and their reheating for thixoforming were studied. Electromagnetic stirring was used to fabricate PMMCs to vary particle size. PMMCs were tested before and after the reheating process using a tensile test with and without heat treatment. The combined process conditions for fabricating the PMMCs are also suggested for a variety of particle sizes. For the thixoforming of PMMCs, fabricated billets are reheated by using an induction heating system with a maximum capacity of 20 kW. The effects of the dispersion state of the reinforcements on the reheating temperature and microstructural morphology were investigated.     

半固态A356合金的二次加热工艺研究

在二次加热过程中,为了使坯料中的温度均匀分布并获得细小的球化组织,必须准确控制加热电流、加热时间与坯料温度之间的关系。以A356合金为对象,采用中频电磁感应器进行了二次加热工艺的研究。结果表明,对于尺寸为45mm×70mm的棒状坯料,线圈尺寸取70mm×100mm,加热路线采用三段加热+保温,经过约10min的二次加热,坯料达到了预期的状态,可以满足后续成形的要求。     

镁合金半固态坯料重熔过程数值模拟

选取了有限元软件ANSYS对镁合金半固态坯料重熔过程进行了数值模拟,并采用电磁感应加热方法。该方法不仅可以提高加热速度,还能使温度均匀化。通过改变电流密度、加热时间、初始温度及频率等参数,找出加热参数与坯料重熔参数之间的关系,以取得通过控制加热工艺参数来获取理想的镁合金半固态坯料组织的理论依据,从而指导生产过程。将所模拟的几组数据比较,选择电流密度为15e6Mm^2,对生产比较有利。考虑到实际的条件。提出了较低电流密度与多极加热结合的想法指导生产。     

连铸坯在加热炉内的温度场数值模拟

采用MSC.Marc有限元模拟软件对加热钢坯进行埋偶试验,得出加热炉内部的实际炉气温度,并以此为边界条件。以钢坯入加热炉时的温度为初始条件,建立钢坯在加热炉内的三维温度场模型;计算钢坯在步进式加热炉内的温度场变化情况,得出不同热装温度的钢坯在加热炉内的温度变化;优化实际生产中的加热工艺。该研究为提高工厂生产效率,节约能源起到指导作用。